1H-indazole and 2H-indazole derivatives of androsta-5,16-dien-3beta-ol.

The title compounds, 17-(1H-indazol-1-yl)androsta-5,16-dien-3beta-ol, (I), and 17-(2H-indazol-2-yl)androsta-5,16-dien-3beta-ol, (II), both C(26)H(32)N(2)O, have an indazole substituent at the C17 position. The six-membered B ring of each compound assumes a half-chair conformation. A twist of the steroid skeleton is observed and reproduced in quantum-mechanical ab initio calculations of the isolated molecule using a molecular orbital Hartree-Fock method. In the 1H-indazole derivative, (I), the molecules are joined in a head-to-head fashion via O-H...O hydrogen bonds, forming chains along the a axis. In the 2H-indazole derivative, (II), the molecules are joined in a head-to-tail fashion with one of the N atoms of the indazole ring system acting as the acceptor. The hydrogen-bond pattern consists of zigzag chains running along the b axis. Substituted steroids have proven to be effective in inhibiting androgen biosynthesis through coordination of the Fe atoms of some enzymes, and this study shows that indazole-substituted steroids adopt twisted conformations that restrict their intermolecular interactions.